WPF DataGrid TemplateColumn，带有CheckBoxes，并使用MVVM Light在标题中选择All -checkbox

<DataGrid x:Name=\"dgReportList\" ItemsSource=\"{Binding Path=ReportListItems}\">
<DataGrid.Columns>
    <DataGridTextColumn Header=\"*SomeText\"  Binding=\"{Binding Path=SourceReport.Name}\" />
    <DataGridTemplateColumn>
        <DataGridTemplateColumn.Header>
            <CheckBox IsChecked=\"{Binding Source={StaticResource Locator},     
                  Path=MainWindowViewModel.CheckAll, Mode=TwoWay, 
                  UpdateSourceTrigger=PropertyChanged}\"  />
        </DataGridTemplateColumn.Header>
        <DataGridTemplateColumn.CellTemplate>
            <DataTemplate>
                <CheckBox IsChecked=\"{Binding Path=IsSelected, Mode=TwoWay, 
             UpdateSourceTrigger=PropertyChanged}\">                                    
          </CheckBox>
            </DataTemplate>
        </DataGridTemplateColumn.CellTemplate>
   </DataGridTemplateColumn>

    private ObservableCollection<ReportListItemModel> _reportListItems;

    public ObservableCollection<ReportListItemModel> ReportListItems
    {
        get
        {
            return this._reportListItems;
        }
        private set
        {
            this._reportListItems = value;
            this.RaisePropertyChanged(\"ReportListItems\");
        }
    }

    ....

    public bool CheckAll
    {
        get { return this._checkall; }
        set 
        {
            this._checkall = value; 

            foreach (var reportListItemModel in ReportListItems)
            {
                reportListItemModel.IsSelected = this._checkall;
            }
        }
    }

public class ReportListItemModel
{
    public EnvironmentConfigurationModel TargetConfigurationModel { get; set; }
    public ReportModel TargetReport { get; set; }

    public EnvironmentConfigurationModel SourceConfigurationModel { get; set; }
    public ReportModel SourceReport { get; set; }

    private bool _isSelected;

    public bool IsSelected
    {
        get { return _isSelected; }
        set 
        {
            _isSelected = value;
        }
    }
}